Adjustable resection guide

ABSTRACT

An adjustable resection guide is provided for guiding cutting of the tibia and/or femur during knee replacement surgery.

BACKGROUND

The invention relates to resection guides for guiding a cutter to cut abone to receive a knee prosthesis. More particularly, the inventionrelates to adjustable resection guides.

Degenerative and traumatic damage to the articular cartilage of the kneejoint can result in pain and restricted motion. Prosthetic jointreplacement is frequently utilized to alleviate the pain and restorejoint function. In this procedure, the damaged compartments of the jointare cut away and replaced with prosthetic components. Typically aresection guide is used to guide a cutter such as a saw blade or bur tocut a desired portion of the bone.

SUMMARY

The present invention provides a resection guide for guiding cutting ofthe tibia and/or femur during knee replacement surgery.

In one aspect of the invention, an adjustable resection guide includesan elongated base member, a tibial cut guide, and mediolateral andproximal-distal adjustment mechanisms. The tibial cut guide has a guidesurface for guiding a cutter to cut the tibia. The mediolateral andproximal-distal adjustment mechanisms are interposed between the basemember and tibial cut guide to permit the tibial cut guide to bepositioned at a desired location adjacent the proximal tibia.

In another aspect of the invention, an adjustable resection guideincludes a tibial cut guide having means for guiding a cutter to cut thetibia and a femoral cut guide having means for guiding a cutter to cutthe femur. The femoral cut guide is mounted on the tibial cut guide inrelative mediolateral translating relationship.

In another aspect of the invention, an adjustable resection guideincludes a base member and a tibial cut guide mounted on the base memberin relative proximal-distal translating relationship. A firstproximal-distal adjustment mechanism is for making coarse adjustments inthe relative proximal-distal position of the tibial cut guide relativeto the base member and a second proximal-distal adjustment mechanism isfor making fine adjustments in the relative proximal-distal position ofthe tibial cut guide relative to the base member.

In another aspect of the invention, an adjustable resection guideincludes an elongated base member, a rod, a support member, and tibialcut guide. The base member includes an axial bore opening axiallyoutwardly at its proximal end. The rod has a dovetail engagement formedon its proximal end and its distal end is received in the base memberaxial bore for axial translation. The support member has an outwardlyopening radial slot and an axial bore communicating with the radialslot. The support member has a dovetail engagement formed on its distalend that engages the dovetail engagement of the rod for mediolateraltranslation. The tibial cut guide has a guide surface for guiding acutter to cut the tibia and a support arm extending distally from thetibial cut guide. The support arm is received by the axial bore of thesupport member for axial translation. A portion of the support arm isthreaded and engages a nut positioned within the radial slot of thesupport member such that rotating the nut causes the tibial cut guide totranslate proximal-distally.

In another aspect of the invention, a method for guiding a cutter to cutbone adjacent a knee joint includes providing a resection guidecomprising a tibial cut guide having means for guiding a cutter to cutthe tibia and a femoral cut guide mountable on the tibial cut guide, thefemoral cut guide comprising an outwardly projecting paddle and meansfor guiding a cutter to cut the femur, positioning the resection guideadjacent the tibia, mounting the femoral cut guide on the tibial cutguide, inserting the paddle into the joint space between the tibia andfemur, and adjusting the proximal-distal position of the tibial andfemoral resection guides together until the paddle abuts the femoralcondyle.

In another aspect of the invention, a method for guiding a cutter to cutbone adjacent a knee joint includes providing a resection guidecomprising an elongated base member having a longitudinal axis, the basemember having a proximal end and a distal end, the base member beingpositionable adjacent the tibia with the longitudinal axis parallel tothe tibial axis, a tibial cut guide having means for guiding a cutter tocut the tibia, and a stylus mountable on the tibial cut guide, thestylus having a reference surface for engaging the articulating end ofthe tibia, the tibial cut guide being mounted on the base member with amediolateral adjustment mechanism interposed between the base member andthe tibial cut guide, the mediolateral adjustment mechanism operable toadjust the tibial cut guide mediolaterally relative to the base member,and a proximal-distal adjustment mechanism interposed between the basemember and the tibial cut guide, the proximal-distal adjustmentmechanism operable to adjust the tibial cut guide proximal-distallyrelative to the base member, the proximal-distal adjustment mechanismcomprising separate coarse adjustment and fine adjustment mechanisms,positioning the base member adjacent the tibia, mounting the stylus onthe tibial cut guide, inserting the stylus into the joint space betweenthe tibia and femur, adjusting the proximal-distal position of thetibial cut guide using the coarse and fine adjustment mechanisms untilthe stylus reference surface abuts the proximal tibial surface, andadjusting the mediolateral position of the tibial cut guide relative tothe base to position the tibial cut guide in a desired mediolateralposition.

In another aspect of the invention, a method for guiding a cutter to cutbone adjacent a knee joint includes providing a resection guidecomprising a tibial cut guide having means for guiding a cutter to cutthe tibia, a femoral cut guide mounted on the tibial cut guide inrelative mediolateral translating relationship, the femoral cut guidecomprising means for guiding a cutter to cut the femur, positioning theresection guide adjacent the tibia, translating the tibial cut guidemediolaterally to a desired mediolateral position relative to the tibia,and translating the femoral cut guide mediolaterally relative to thetibial cut guide to a desired mediolateral position relative to thefemur.

BRIEF DESCRIPTION OF THE DRAWINGS

Various embodiments of the present invention will be discussed withreference to the appended drawings. These drawings depict onlyillustrative embodiments of the invention and are not to be consideredlimiting of its scope.

FIGS. 1-3 are exploded perspective views of an illustrative adjustableresection guide according to the present invention;

FIG. 4 is a side plan view of the resection guide of FIGS. 1-3 assembledwith an optional illustrative femoral cut guide and positioned on abone;

FIG. 5 is a front plan view of the upper portion of the assembledresection guide of FIG. 4 and positioned on a bone; and

FIG. 6 is a side plan view of the upper portion of the resection guideof FIGS. 1-3 assembled with an optional illustrative tibial stylus andpositioned on a bone.

DESCRIPTION OF THE ILLUSTRATED EMBODIMENTS

FIGS. 1-6 depict an illustrative adjustable resection guide 10 having atibial cut guide 100, a support assembly 200, and an ankle clampassembly 300 that interconnect to permit a variety of adjustments in thesize and position of the resection guide 10. An optional modular femoralcut guide 400 and tibial depth setting stylus 500 are also shown. Theuse of the femoral cut guide 400 and stylus 500 with the adjustableresection guide 10 will be discussed after the basic form and functionof the resection guide 10 has been fully described. Throughout thisdescription the term proximal will be used to refer to locations nearerthe hip joint and distal will be used to refer to locations further fromthe hip joint. Thus the inferior most portion of the femur in extensionis the femoral condyle and the superior most portion of the tibia is theproximal tibial surface. Likewise, upper portions of the instruments asthey would be mounted on the tibia are referred to as proximal and lowerportions are referred to as distal.

In FIG. 4, the resection guide 10 is depicted in use cutting the distalfemur and proximal tibia with the knee in extension. However, theresection guide 10 may also be used to cut the knee in other degrees offlexion such as 90°, 45° and other suitable angles. Also, the resectionguide 10 may be used to make other femoral cuts such as the posteriorfemoral cut, chamfer cuts, and other suitable cuts.

The tibial cut guide 100 (FIG. 1) includes a head 102 having an anterioraspect 101, a posterior aspect 103, and a proximal aspect 105. The head102 includes a guide surface in the form of a cut slot 104 extendingthrough the head from the anterior aspect 101 to the posterior aspect103 for guiding a blade to cut the tibia. The guide surface may takeother forms including open planar surfaces, line contact bearingsurfaces, and other suitable guide surfaces. A support arm 106 extendsdistally from the head 102 from a proximal end 108 adjacent the head 102to a distal end 110 spaced from the head 102. The head 102 and supportarm 106 may be formed separately or as an integral piece as shown in theillustrative embodiment. The distal end 110 of the support arm isaligned along a vertical axis 111 and includes a bearing portion 112having a non-circular cross section that connects to the supportassembly 200 (FIG. 2). The non-circular cross section prevents rotationof the tibial cut guide 100 relative to the support assembly whilepermitting axial translation for height adjustment. The distal end 110of the support arm further includes a mounting post 114 having aproximal threaded proximal portion 116 and a distal smooth portion 118.The threaded portion 116 is received by the support assembly 200 (FIG.2) to provide fine control for adjusting the height of the tibial cutguide 100 relative to the support assembly 200. The smooth portion 118is received by the support assembly 200 to provide increasedside-to-side stability to the tibial cut guide 100 on the supportassembly 200. The proximal end 108 of the support arm 106 is offsetposteriorly relative to the distal end 110 so that the head 102 isoffset posteriorly.

The tibial cut guide 100 includes one or more fixation holes 120 forreceiving pins, screws, or other suitable fixation members to anchor thetibial cut guide 100 to the tibia prior to cutting the tibia. Thefixation holes 120 may be provided at any suitable location on thetibial cut guide 100 as long as they anchor the tibial cut guide 100securely. In the illustrative embodiment, the fixation holes 120 arelocated just below the cut slot 104 and extend through the head 102 fromthe anterior aspect 101 to the posterior aspect 103. The forces tendingto move the cut guide 100 in use are caused by pressure from a cutteragainst the edges of the cut slot 104. Placement of the fixation holes120 close to the cut slot 104 minimizes the moment arm over which theforces act and thus provides maximum stability. Placement of thefixation holes 120 close to the cut slot 104 also reduces the overallincision length required to resect the tibia as it permits fixationmembers to be placed in the same incision through which the boneresection takes place. This is especially useful in a minimally invasivesurgical approach since it avoids having to lengthen the incision orcreate separate percutaneous punctures.

The tibial cut guide 100 further includes a femoral cut guide engagementportion in the form of a dovetail slot 122 formed mediolaterally on theproximal aspect 105 of the head 102 to receive dovetail rails from thefemoral cut guide 400 in medial/lateral sliding arrangement. A portion123 of the anterior side of the dovetail slot is relieved to easeattachment and detachment of the cut guide 400 as will be discussed morefully below. Although the illustrative embodiment has depicted the head102 with a dovetail slot 122, the slot and rail arrangement may bereversed or a different attachment mechanism may be provided forconnecting the optional femoral cut guide 400. The tibial cut guide 100further includes a depth stylus engagement portion in the form of anaxial bore 124 formed in the proximal aspect 105 of the head 102 forreceiving a mounting post 504 on the tibial depth setting stylus 500.Although the illustrative embodiment has depicted an axial bore 124 inthe head 102, the bore and post arrangement may be reversed or adifferent attachment mechanism may be provided for connecting theoptional stylus 500.

The support assembly 200 (FIG. 2) includes a resection guide base 202having a proximal end 204, a distal end 206 and an axis 208therebetween. A non-circular bore 210 and a round bore 212 are alignedalong the axis 208 to receive the distal end 110 of the support arm ofthe tibial cut guide 100. A slot 214 is positioned axially between thebores 210, 212 to receive a fine height adjustment knob 216 having anaxial threaded bore 218. The knob 216 is free to rotate about the axis208 within the slot 214 but is prevented from moving up and down alongthe axis by impingement with the top 220 and bottom 222 of the slot 214.The non-circular bore 210 of the resection guide base 202 receives thenon-circular bearing portion 112 of the tibial cut guide 100 in axialsliding arrangement. The threaded bore 218 of the knob 216 receives thethreaded portion 116 of the mounting post 114 of the tibial cut guide100 for positive height control of the tibial cut guide 100 relative tothe resection guide base 202. The round bore 212 receives the smoothportion 118 of the mounting post 114 of the tibial cut guide 100 forincreased side-to-side stability of the tibial cut guide 100. Whenassembled (FIG. 5), the side of the knob 216 extends from the slot 214to permit rotation of the knob 216 by thumb pressure from a user to movethe tibial cut guide 100 axially up-and-down relative to the resectionguide base 202.

A fixation arm 226 projects upwardly from the proximal end 204 of theresection guide base 202 to a terminal end 228. The terminal end 228 isoffset posteriorly such that the fixation arm 226 lies beside thesupport arm 106 of the tibial cut guide 100 and the terminal end 228lies beside the head 102 of the tibial cut guide 100 when they areassembled (FIG. 5). The terminal end 228 includes one or more fixationholes 230 to receive fixation members for securing the resection guidebase 202 to the tibia.

An elongated platform 232 is attached to the resection guide base 202 atits distal end 206. The platform 232 extends mediolaterally and includesa sliding attachment portion in the form of a mediolaterally extendingdovetail slot 234 for receiving a distal extension rod 236. The distalextension rod 236 includes an elongated non-circular shaft 237 forconnecting the resection guide base 202 to the ankle clamp assembly(FIG. 3). The extension rod 236 includes a proximal end 238, a distalend 240, and a longitudinal axis 242 extending therebetween. Dovetailrails 244 are formed at the proximal end 238 and are received by thedovetail slot 234 of the resection guide base 202 to permit mediolateralrelative translation between the extension rod 236 and the resectionguide base 202. A slot 246 extends from the proximal end 238 of theextension rod 236 distally to divide the dovetail rails 244 into twoseparate leaves 245 to provide a locking mechanism for fixing therelative position of the extension rod 236 and the resection guide base202. One of the leaves 245 includes a threaded through bore 248 forreceiving a locking knob 250. The locking knob 250 includes a shaft 252having a threaded portion 254 and an end 256. The locking knob 250 isthreaded into the threaded bore 248 of one of the leaves 245 until theend 256 of the shaft 252 contacts the opposite leaf 245. Furthertightening of the locking knob 250 causes the leaves 245 to separatesuch that the dovetail rails 244 expand and grip the dovetail slot 234to lock the relative position of the extension rod 236 and resectionguide base 202. The illustrative embodiment has been shown with adovetail slot 234 on the resection guide base 202 and dovetail rails 244on the extension rod 236. However, the slot and rail arrangement may bereversed and/or other suitable connections may be provided to permitmediolateral adjustability.

The ankle clamp assembly 300 (FIG. 3) includes an ankle clamp base 302having a proximal end 304, a distal end 306, and an axis 308 extendingbetween the proximal and distal ends 304, 306. An axial non-circularbore 310 extends distally from the proximal end 304 to receive thedistal extension rod 236 for axial translation. The non-circular shapeof the bore 310 and extension rod 236 prevent the extension rod 236 fromrotating relative to the ankle clamp base 302. Other shapes andmechanisms may also be used to prevent relative rotation of these parts.A boss 312 extends from the ankle clamp base 302 normal to the axis 308near the proximal end 304. The boss 312 includes a threaded through borecommunicating with the axial non-circular bore 310. A vertical, orproximal-distal, coarse adjustment locking knob 314 includes a shaft 316having a threaded portion 318 and an end 320. The locking knob 314 isthreaded into the boss 312 until the end 320 of the shaft 316 lightlycontacts the extension rod 236 of the support assembly 200. Furthertightening of the locking knob 314 against the extension rod 236 locksthe vertical position of the extension rod 236 relative to the ankleclamp assembly 300.

A proximal extension arm 301 extends anteriorly from the ankle clampbase 302 and includes a proximal alignment rod hole 303. A distalextension arm 305 extends anteriorly from the ankle clamp base 302 andincludes a distal alignment rod hole 307. An alignment rod (not shown)may optionally be positioned in the alignment rod holes 303, 307 to helpvisualize proper leg positioning such as alignment of the tibial axiswith the center of the femoral head.

The distal end 306 of the ankle clamp base 302 is shaped into a distallydirected pointer 322 to aid in aligning the ankle clamp assembly axis308 with the center of a patients ankle. An anteroposterior through bore324 in the distal end 306 receives an ankle clamp mounting post 326 foranteroposterior adjustment of the distal end 306. The bore 324 is keyed,for example with flat sides as shown, to prevent rotation of themounting post 326 within the bore 324. The mounting post 326 includes ashaft having a cross sectional shape corresponding to the bore 324 andextending from an anterior end 328 to a posterior end 330. Amediolateral extending dovetail rail 332 is attached to the posteriorend 330 of the mounting post 326. A threaded bore 334 extends throughthe mounting post 326 from the anterior end 328 to the posterior end 330and on through the dovetail rail 332. An ankle clamp 340 includes a base342 having a dovetail slot 344 extending between opposite sides 346, 348of the base 342 for receiving the dovetail rail 332 of the mounting post326 to permit mediolateral translation of the ankle clamp relative tothe mounting post 326. A curved arm 350 having an attachment end 352 anda gripping end 354 attaches to each end 346, 348 of the clamp base 342with a pivot pin 356. A coil spring 358 biases each arm 350 inwardlytoward the other. With the mounting post 326 received within the bore324 of the ankle clamp base 302, the ankle clamp 340 may be translatedanteriorly and posteriorly by sliding the mounting post 326 in the bore324. A threaded through bore 360 in the distal end 306 of the ankleclamp base 302 communicates with the bore 324 and receives ananterior/posterior (A/P) locking knob 362. The A/P locking knob 362includes a shaft 364 having a threaded portion 366 and an end 368. Thelocking knob 362 is threaded into the threaded bore 360 until the end368 of the shaft 364 lightly contacts the mounting post 326. Furthertightening of the locking knob 362 against the mounting post 326 locksthe A/P position of the mounting post 326 relative to the ankle clampbase 302. With the ankle clamp 340 assembled to the mounting post 326,the ankle clamp 340 may be translated mediolaterally by sliding thedovetail slot 344 over the dovetail rail 332. The threaded bore 334 ofthe mounting post 326 receives a medial/lateral (ML) locking knob 370.The M/L locking knob 370 includes a shaft 372 having a threaded portion374 and an end 376. The locking knob 370 is threaded into the threadedbore 334 until the end 376 of the shaft 372 lightly contacts thedovetail slot 344 of the ankle clamp 340. Further tightening of thelocking knob 370 against the dovetail slot 344 locks the M/L position ofthe ankle clamp 340 relative to the ankle clamp base 302.

An illustrative optional modular femoral cut guide 400 is depicted inFIGS. 1, 4, and 5. The cut guide 400 includes a body 402 having aproximal aspect 404, a distal aspect 406, an anterior aspect 408, aposterior aspect 410, and sides 412, 414. The cut guide 400 includes aguide surface in the form of a cut slot 416 extending through the cutguide 400 from the anterior aspect 408 to the posterior aspect 410between the sides 412, 414 for guiding a blade to cut the femur. Theguide surface may take other forms including open planar surfaces, linecontact bearing surfaces, and other suitable guide surfaces. A femoralreference paddle 411 extends from the posterior aspect 410 of the body402 at a predetermined spacing distally of the cut slot 416. The paddle411 includes a top surface 413 that may be abutted against the femoralcondyle to position the cut slot 416 to remove a predetermined amount ofbone from the femoral condyle or alternatively to space the tibial cutslot 104 a predetermined distance from the femoral condyle. The paddle411 tapers posteriorly to a thin tip 415 to facilitate insertion intothe joint space between the tibia and femur. The paddle 411 may bepermanently attached (as shown) or modular (not shown). A modular paddle411 may be provided to ease assembly and insertion of the adjustableresection guide 10 into the surgical wound. A modular paddle 411 alsomay be removed after the cut depth is set to permit the knee to beflexed while the cut guide 400 remains in place. A modular paddle 411also permits omitting the paddle 411 in cases where the cut depth is setin another manner such as by referencing the tibia. A permanentlyattached paddle 411 may be formed as an integral part of the cut guide400, welded to the cut guide, or attached in another suitable way. Amodular paddle 411 may be bolted onto the cut guide 400, snapped in,carried in a slot, or otherwise attached to the cut guide 400. Forexample, one or more additional slots may be provided at a predeterminedspacing distal to the cut slot 416 and extending from the anterioraspect to the posterior aspect. The paddle 411 may be inserted throughthe second slot from the anterior aspect 408 to the posterior aspect410.

An attachment member in the form of a dovetail rail 418 projects fromthe distal aspect 406 of the cut guide 400 and extends mediolaterallyalong the distal aspect 406. The dovetail rail 418 is received by thedovetail slot 122 of the tibial cut guide head 102 for mediolateraltranslation of the femoral cut guide 400 relative to the tibial cutguide 100. The dovetail engagement maintains the angle and spacingbetween the cutting guide surfaces of the femoral and tibial cut guides400, 100 constant while permitting mediolateral translation. Thedovetail rail 418 extends mediolaterally a distance less than thedistance between the sides 412, 414 of the femoral cut guide 400 and thedovetail slot 122 extends only part way across the proximal aspect ofthe tibial cut guide head 102 to facilitate mounting the femoral cutguide 400 on the tibial cut guide 100 without requiring extreme relativemediolateral positioning of the cut guides 100, 400. The relievedportion 123 of the dovetail slot 122 further facilitates mounting thefemoral cut guide 400. To mount the femoral cut guide 400 on the tibialcut guide 100, the dovetail rail 418 is positioned to just clear theside of the dovetail slot 122 adjacent the relieved portion 123. In thisposition the mediolateral width of the positioned cut guides 100, 400 ismuch less than the combined widths of the individual cut guides 100, 400and much less than would be the width of the positioned cut guides 100,400 if the dovetail rail and slot 418, 122 extended across the fullwidth of the cut guides 400, 100 and/or if the relieved portion 123 wasnot provided. This arrangement permits the femoral cut guide 400 to bemounted on the tibial cut guide 100 within the confines of a narrowincision such as the incision used in a minimally invasive approach toknee surgery. The femoral cut guide 400 is translated posteriorly untilthe dovetail rail 418 engages the dovetail slot 122 opposite therelieved portion 123. The femoral cut guide 400 is translatedmediolaterally to engage the dovetail slot 122 adjacent the relievedportion 123. As described relative to the dovetail slot 122, thedovetail members may be reversed or other attachment mechanisms may beused. With the femoral cut guide 400 attached to the tibial cut guide100, the femoral and tibial cut slots 416, 104 are positioned to guidecutters to remove a portion of the femur and tibia to create apredetermined gap for receiving an implant. Fixation holes 420 receivepins, screws, or other fixation members to attach the femoral cut guideat a desired location on the femur.

An illustrative optional tibial depth setting stylus 500 is depicted inFIGS. 1 and 6. The stylus 500 includes a mounting base 502. A mountingpost 504 extends distally from the mounting base 502 and includes a balldetent 505 for secure attachment of the stylus 500 to the tibial cutguide 100. A threaded post 506 extends proximally from the mounting base502. A reference arm 508 includes a body 510 having a longitudinal slot512 and opposite first and second reference tips 514, 516. The first andsecond tips 514, 516 are offset different distances distally from thebody 510. The reference arm slot 512 receives the mounting base threadedpost 506 and the reference arm 508 is secured to the mounting base 502with a nut 518 and a washer 520. The stylus 500 is mounted on the tibialcut guide 100 by inserting the mounting post 504 into the axial bore 124formed in the head 102 of the tibial cut guide 100. The ball detent 505is biased outwardly by a captured spring (not shown) such that as themounting post 504 is inserted, the ball detent 505 is forced back intothe mounting post 504. As the ball detent 505 aligns with the cut slot104, the ball detent 505 is biased into engagement with the slot 104 tosecure the stylus 500 in a predetermined axial spacing from the cut slot104. In this position, the first and second stylus tips 514, 516 arepositioned at predetermined axial distances from the cut slot 104. Byalternately positioning the first and second tips 514, 516 against theproximal tibial surface, the cut slot 104 may be positioned at twodifferent predetermined cut depths to guide a cutter to remove differentamounts of bone from the proximal tibial surface.

The above described instruments permit a variety of uses. They provideflexibility in mediolateral, anteroposterior, and proximal-distalpositioning of the cut guides on the bone. They provide for referencingthe proximal tibia and/or femur for establishing resection levels. Theyfurther provide for linked cutting of the tibia and femur or separateunlinked cutting of the tibia and femur.

The multiple mechanisms for mediolateral adjustment of the differentportions of the instruments permit the instruments to be used in amidline position as in a total condylar knee surgery, in a medialposition on a left or right knee in a unicondylar knee surgery, and in alateral position on a left or right knee in a unicondylar knee surgery.The mediolateral adjustment at the ankle facilitates proper alignment ofthe distal portion of the instrument with the tibial axis. Themediolateral adjustment in the support assembly 200 permits alignment ofthe tibial cut guide 100 medially, centrally, or laterally on a left orright knee. Finally, the mediolateral adjustment between the femoral cutguide 400 and the tibial cut guide 100 permits the femoral cut guide 400to be adjusted mediolaterally independently of the tibial cut guide 100to optimize femoral cut guide 400 alignment on the femur.

The instrument incorporates both coarse and fine height adjustment toallow for rapid and accurate height settings. The support assembly 200extension rod 236 may be slid proximal-distally within the ankle clampassembly 300 for rapid height adjustment and gross positioning of thecut guides 100, 400. The screw mechanism controlled by the fine heightadjustment knob 216 may then be used to fine tune the resection levelsby positively dialing in the desired height.

The anteroposterior adjustment of the ankle clamp assembly 300 permitsaccurate positioning of the resection guide 10 parallel to the tibialaxis to insure accurate anteroposterior resection slopes. Theseadvantages and others will be apparent from the following description ofillustrative surgical techniques.

In one exemplary surgical technique, the resection levels are set byreferencing a femoral condyle 600 of a femur 602. This technique will bebest understood by referring to FIGS. 4 and 5 showing the assembledadjustable resection guide 10 including the femoral cut guide 400. Afterexposing a portion of the knee joint the adjustable resection guide 10is positioned adjacent the tibia 604. The arms 350 of the ankle clamp340 are spread open and placed around the ankle 606. The coil springs358 bias the arms to grip the ankle 606. The ankle clamp assembly 300 isaligned with the center of the ankle 606 by positioning the pointer 322over the center of the ankle 606. The dovetail rail 332 is slidmediolaterally as necessary within the dovetail slot 344 of the ankleclamp 340. Once the assembly 300 is aligned, the MIL adjustment knob 370is tightened to extend the end 376 of the shaft 372 and lock themediolateral adjustment. Similarly, the anteroposterior position of theankle clamp assembly 300 is adjusted so that the ankle clamp base 302 isparallel to the tibial axis 608. The A/P adjustment knob 362 is thentightened to lock the anteroposterior adjustment. With the coarseproximal-distal adjustment knob 314 loosened, the tibial cut guide 100and support assembly 200 are adjusted to bring the tibial cut guide 100into rough alignment with the approximate tibial resection level. Thisrough setting is locked by tightening the coarse adjustment knob 314.The mediolateral position of the tibial cut guide 100 and supportassembly is adjusted by sliding the dovetail slot 234 of the supportassembly 200 over the dovetail rail 244 of the extension rod 236. Themediolateral position is locked by tightening the M/L adjustment knob250. The support assembly 200 is now secured to the tibia by drivingfixation members through the fixation holes 230. Because of theproximity of the fixation holes 230 to the tibial cut guide head 102,the fixation members may be positioned within the incision made toexpose the joint. The support assembly 200 and ankle clamp assembly 300are now aligned and well fixed to the tibia 604 to provide a stableplatform for subsequent instrument positioning. The femoral cut guide400 is mounted on the tibial cut guide 100 by inserting the paddle 411in the joint space between the femur 602 and tibia 604 and positioningthe dovetail rail 418 adjacent the relieved portion 123 of the dovetailslot 122. The femoral cut guide 400 is translated posteriorly until thedovetail rail 418 engages the dovetail slot 122 opposite the relievedportion 123. The femoral cut guide 400 is translated mediolaterally toengage the dovetail slot 122 adjacent the relieved portion 123. With thefemoral cut guide 400 mounted on the tibial cut guide 100, the fineheight adjustment knob 216 is rotated to move the femoral cut guide 400and tibial cut guide 100 as a single unit until the top surface 413 ofthe paddle 411 contacts the femoral condyle 600 with the leg in properalignment. With the resection height now set, the surgeon has severalsurgical options.

A first option would be to fix both cut guides 100, 400 in place and cutboth the femur 602 and the tibia 604 with the knee in extension. Thetibial cut guide 100 is fixed in place by inserting fixation membersthrough the fixation holes 120 in the tibial cut guide 100. The femoralcut guide 400 is adjusted mediolaterally by sliding the dovetail rail418 in the dovetail slot 122 until the desired mediolateral position ofthe cut guide is reached. The femoral cut guide 400 is then fixed inplace by inserting fixation members through the fixation holes 420 inthe femoral cut guide 400. A cutter is guided through the tibial andfemoral cut slots 104, 416 to remove portions of the tibia 604 and femur602.

A second option would be to fix both cut guides 100, 400 and cut thefemur 602 with the knee in extension. After the femur 602 has been cut,the femoral cut guide 400 is removed by removing the fixation membersand sliding the femoral cut guide 400 until the dovetail rail 418 justclears the relieved portion 123 of the dovetail slot 122 and translatingthe femoral cut guide 400 anteriorly. The knee is then flexed to aconvenient angle and the tibia 604 is cut. Both the first and secondoptions are linked cuts in that the spacing between the cuts isestablished with the cut guides joined together in fixed predeterminedspaced relationship.

A third option would be to cut either the tibia 604 or femur 602 at thisstage and then use another technique to cut the other bone. For example,the tibial cut guide may be secured to the tibia 604 and the proximaltibial surface 610 may be resected. The adjustable resection guide 10may then be removed and the femur 602 may be cut using another techniquesuch as using spacer blocks as is known in the art. All three of theseoptions rely on referencing the femoral condyle 600 to set the resectionheight for the femoral and/or tibial cuts.

In another exemplary surgical technique, the resection level isestablished by referencing the proximal tibial surface 610. Thistechnique will be best understood by referring to FIG. 6 showing theassembled adjustable resection guide 10 including the tibial depthsetting stylus 500. After exposing a portion of the knee joint theadjustable resection guide 10 is positioned adjacent the tibia 604 andthe rough mediolateral, anteroposterior, and proximal-distal adjustmentsare made as described relative to the femoral referencing technique.However, rather than attaching the femoral cut guide 400, the tibialstylus 500 is attached to the tibial cut guide 100 by snapping themounting post 504 into the bore 124 in the tibial cut guide 100. Thedesired amount of tibial resection is established by positioning theappropriate tip 514, 516 of the reference arm 508 over the proximaltibial surface 610. The fine height adjustment knob 216 is rotated tomove the stylus 500 and tibial cut guide 100 as a single unit until oneof the tips 514, 516 contacts the proximal tibial surface 610. Thetibial cut guide 100 is now positioned to remove a predetermined amountof bone. The tibial cut guide 100 is secured to the tibia 604 byinserting fixation members through the fixation holes 120 and theproximal tibial surface 610 is resected by guiding a cutter through thetibial cut slot 104. The femoral cut guide 400 may be attached to thetibial cut guide 100 to set the femoral resection height. In this case,the cuts would be linked and based on tibial referencing. Alternatively,the femoral cut may be made using another technique such as using spacerguides.

It will be understood by those skilled in the art that the foregoing hasdescribed illustrative embodiments of the present invention and thatvariations may be made to these embodiments without departing from thespirit and scope of the invention defined by the appended claims.

1. An adjustable resection guide for guiding a cutter to cut boneadjacent a knee joint to prepare the bone to receive an implant, theknee joint including articulating ends of a tibia and a femur and havinga medial aspect, a lateral aspect, an anterior aspect, and a posterioraspect, the tibia having a tibial axis extending from a proximal endnear the knee joint to a distal end near an ankle joint, the guidecomprising: an elongated base member having a proximal end, a distal endand a longitudinal axis therebetween, the base member being positionableadjacent the tibia with the longitudinal axis parallel to the tibialaxis; a tibial cut guide having a guide surface for guiding a cutter tocut the tibia; a mediolateral adjustment mechanism interposed betweenthe base member and the tibial cut guide, the mediolateral adjustmentmechanism operable to adjust the tibial cut guide mediolaterallyrelative to the base member; and a proximal-distal adjustment mechanisminterposed between the base member and the tibial cut guide, theproximal-distal adjustment mechanism operable to adjust the tibial cutguide proximal-distally relative to the base member independently of themediolateral adjustment, the mediolateral and proximal-distal adjustmentmechanisms permitting the tibial cut guide to be positioned at a desiredlocation adjacent the proximal tibia.
 2. The resection guide of claim 1wherein the proximal-distal adjustment mechanism comprises separatecoarse adjustment and fine adjustment mechanisms.
 3. The resection guideof claim 2 wherein the fine adjustment mechanism comprises male andfemale threaded members associated with the base member and tibial cutguide, the threaded members being threaded together such that turningone of the threaded members causes the tibial cut guide to translaterelative to the base member in a direction parallel to the longitudinalaxis of the base member.
 4. The resection guide of claim 3 wherein thecoarse adjustment mechanism comprises elongated members associated withthe base member and tibial cut guide, the elongated members beingtelescoped together for relative translation in a direction parallel tothe longitudinal axis of the base member.
 5. The resection guide ofclaim 2 further comprising first fixation means for securing theresection guide to the tibia to fix the coarse proximal-distaladjustment and second fixation means for securing the tibial cut guideto the tibia to fix the fine proximal-distal adjustment.
 6. Theresection guide of claim 1 wherein the mediolateral adjustment mechanismcomprises a dovetail slot and a dovetail rail mounted for relativemediolateral sliding and a clamping mechanism for clamping the dovetailrail within the dovetail slot at a desired mediolateral location.
 7. Theresection guide of claim 1 further comprising an ankle clamp coupled tothe distal end of the base member in relative mediolateral translatingrelationship such that the distal end of the base member is adjustablemediolaterally relative to the ankle clamp, the ankle clamp including alocking mechanism for locking the distal end of the base member relativeto the ankle clamp at a desired mediolateral location.
 8. The resectionguide of claim 1 further comprising a modular femoral cut guidemountable on the tibial cut guide in relative mediolateral translatingrelationship, the femoral cut guide having a guide surface for guiding acutter to cut the femur.
 9. The resection guide of claim 8 wherein theguide surface of the femoral cut guide and the guide surface of thetibial cut guide are in fixed proximal-distal spacing while the femoralcut guide is adjusted mediolaterally relative to the tibial cut guide.10. The resection guide of claim 9 wherein the femoral cut guide ismountable on the tibial cut guide via a dovetail rail and slot.
 11. Theresection guide of claim 8 wherein the tibial cut guide has a width andthe femoral cut guide has a width, the femoral cut guide being mountableon the tibial cut guide with a two step motion wherein it istranslatable in an anterior to posterior motion to initially engage thetibial cut guide while the tibial cut guide width is overlapping thefemoral cut guide width and it is translatable in a mediolateral motionto fully engage the tibial cut guide such that the guides are engageablein a space narrower than their combined width.
 12. The resection guideof claim 11 wherein the femoral cut guide is mountable on the tibial cutguide via a dovetail rail and slot, the dovetail rail extendingmediolaterally a distance less than the width of the femoral cut guideand the dovetail slot extending only part way across the tibial cutguide to facilitate mounting the femoral cut guide on the tibial cutguide without requiring extreme relative mediolateral positioning of thecut guides, an anterior portion of the dovetail slot being relieved suchthat the femoral cut guide may be overlapped with the tibial cut guideand engaged by first translating the femoral cut guide posteriorly toengage a portion of the dovetail slot opposite the relieved portion andthen translated mediolaterally to fully engage the dovetail slot. 13.The resection guide of claim 8 wherein the femoral cut guide furtherincludes a paddle extending posteriorly from the cut guide, the paddlebeing engageable with the femur to establish the desired proximal-distallocation of the tibial and femoral cut guides.
 14. The resection guideof claim 13 wherein the paddle is removably mounted on the femoral cutguide.
 15. The resection guide of claim 14 wherein the paddle is mountedin a slot spaced from the guide surface.
 16. The resection guide ofclaim 1 further comprising a modular stylus mountable on the tibial cutguide in fixed proximal-distal relationship, the stylus being engageablewith the tibia to establish a desired proximal-distal location of thetibial cut guide.
 17. An adjustable resection guide for guiding a cutterto cut bone adjacent a knee joint to prepare the bone to receive animplant, the knee joint including articulating ends of a tibia and afemur and having a medial aspect, a lateral aspect, an anterior aspect,and a posterior aspect, the tibia having a tibial axis extending from aproximal end near the knee joint to a distal end near an ankle joint,the resection guide comprising: a tibial cut guide comprising means forguiding a cutter to cut the tibia; a femoral cut guide mounted on thetibial cut guide in relative mediolateral translating relationship, thefemoral cut guide comprising means for guiding a cutter to cut thefemur.
 18. The resection guide of claim 17 wherein the means for guidinga cutter of the femoral cut guide and the means for guiding a cutter ofthe tibial cut guide are in fixed proximal-distal spacing while thefemoral cut guide is adjusted mediolaterally relative to the tibial cutguide.
 19. The resection guide of claim 17 further comprising a basemember alignable parallel to the tibial axis, the tibial cut guide beingmounted on the base member in relative mediolateral translatingrelationship.
 20. The resection guide of claim 19 further comprising anankle clamp, the base member being mounted on the ankle clamp inrelative mediolateral translating relationship.
 21. An adjustableresection guide for guiding a cutter to cut bone adjacent a knee jointto prepare the bone to receive an implant, the knee joint includingarticulating ends of a tibia and a femur and having a medial aspect, alateral aspect, an anterior aspect, and a posterior aspect, the tibiahaving a tibial axis extending from a proximal end near the knee jointto a distal end near an ankle joint, the resection guide comprising: anelongated base member having a longitudinal axis, the base member havinga proximal end and a distal end, the base member being positionableadjacent the tibia with the longitudinal axis parallel to the tibialaxis; a tibial cut guide having a guide surface for guiding a cutter tocut the tibia, the tibial cut guide being mounted on the base member inrelative proximal-distal translating relationship; a firstproximal-distal adjustment mechanism for making coarse adjustments inthe relative proximal-distal position of the tibial cut guide relativeto the base member; and a second proximal-distal adjustment mechanismfor making fine adjustments in the relative proximal-distal position ofthe tibial cut guide relative to the base member.
 22. An adjustableresection guide for guiding a cutter to cut bone adjacent a knee jointto prepare the bone to receive an implant, the knee joint includingarticulating ends of a tibia and a femur and having a medial aspect, alateral aspect, an anterior aspect, and a posterior aspect, the tibiahaving a tibial axis extending from a proximal end near the knee jointto a distal end near an ankle joint, the guide comprising: an elongatedbase member having a proximal end, a distal end, and a longitudinal axistherebetween, the base member being positionable adjacent the tibia withthe longitudinal axis parallel to the tibial axis, the base memberincluding an axial bore opening axially outwardly at the proximal end; arod having a proximal end, a distal end, and a longitudinal axistherebetween, the rod having a dovetail engagement formed on itsproximal end, the distal end of the rod being received in the basemember axial bore for axial translation; a support member having aproximal end, a distal end, and a longitudinal axis therebetween, thesupport member having an outwardly opening radial slot and an axial borecommunicating with the radial slot, the support member having a dovetailengagement formed on its distal end, the dovetail engagement of thesupport member engaging the dovetail engagement of the rod formediolateral translation; a tibial cut guide having a guide surface forguiding a cutter to cut the tibia and a support arm extending distallyfrom the tibial cut guide, the support arm being received by the axialbore of the support member for axial translation, a portion of thesupport arm being threaded; and a threaded nut positioned within theradial slot of the support member and engaged with the threaded portionof the support arm such that rotating the nut causes the tibial cutguide to translate proximal-distally.
 23. A method for guiding a cutterto cut bone adjacent a knee joint to prepare the bone to receive animplant, the knee joint including articulating ends of a tibia and afemur and having a medial aspect, a lateral aspect, an anterior aspect,and a posterior aspect, the tibia having a tibial axis extending from aproximal end near the knee joint to a distal end near an ankle joint,the method comprising: providing a resection guide comprising a tibialcut guide having means for guiding a cutter to cut the tibia and afemoral cut guide mountable on the tibial cut guide, the femoral cutguide comprising an outwardly projecting paddle and means for guiding acutter to cut the femur; positioning the resection guide adjacent thetibia; mounting the femoral cut guide on the tibial cut guide; insertingthe paddle into the joint space between the tibia and femur; andadjusting the proximal-distal position of the tibial and femoralresection guides together until the paddle abuts the femoral condyle.24. The method of claim 23 further comprising: guiding a cutter with thetibial and femoral cut guides to cut the tibia and femur respectivelysuch that the spacing between the tibial and femoral cuts is establishedwith the cut guides connected together and the location of the cuts isreferenced from the femoral condyle.
 25. The method of claim 23 furthercomprising: positioning the knee joint in extension prior to adjustingthe proximal-distal position of the guides; guiding a cutter to cut oneof the tibia and femur while the knee joint is maintained in extension;and flexing the knee joint to cut the other of the tibia and femur suchthat the spacing between the tibial and femoral cuts is established withthe cut guides connected together and the location of the cuts isreferenced from the femoral condyle.
 26. The method of claim 25 whereinthe femur is cut with the knee joint in extension and the tibia is cutwith the knee joint in flexion.
 27. A method for guiding a cutter to cutbone adjacent a knee joint to prepare the bone to receive an implant,the knee joint including articulating ends of a tibia and a femur andhaving a medial aspect, a lateral aspect, an anterior aspect, and aposterior aspect, the tibia having a tibial axis extending from aproximal end near the knee joint to a distal end near an ankle joint,the method comprising: providing a resection guide comprising anelongated base member having a longitudinal axis, the base member havinga proximal end and a distal end, the base member being positionableadjacent the tibia with the longitudinal axis parallel to the tibialaxis, a tibial cut guide having means for guiding a cutter to cut thetibia, and a stylus mountable on the tibial cut guide, the stylus havinga reference surface for engaging the articulating end of the tibia, thetibial cut guide being mounted on the base member with a mediolateraladjustment mechanism interposed between the base member and the tibialcut guide, the mediolateral adjustment mechanism operable to adjust thetibial cut guide mediolaterally relative to the base member, and aproximal-distal adjustment mechanism interposed between the base memberand the tibial cut guide, the proximal-distal adjustment mechanismoperable to adjust the tibial cut guide proximal-distally relative tothe base member, the proximal-distal adjustment mechanism comprisingseparate coarse adjustment and fine adjustment mechanisms; positioningthe base member adjacent the tibia; mounting the stylus on the tibialcut guide; inserting the stylus into the joint space between the tibiaand femur; adjusting the proximal-distal position of the tibial cutguide using the coarse and fine adjustment mechanisms until the stylusreference surface abuts the proximal tibial surface; and adjusting themediolateral position of the tibial cut guide relative to the base toposition the tibial cut guide in a desired mediolateral position. 28.The method of claim 27 further comprising: guiding a cutter to cut thetibia.
 29. The method of claim 27 further comprising: providing afemoral cut guide mountable on the tibial cut guide, the femoral cutguide comprising means for guiding a cutter to cut the femur; mountingthe femoral cut guide on the tibial cut guide such that the spacingbetween the tibial and femoral cuts is established with the cut guidesconnected together and the location of the cuts is referenced from theproximal tibial surface.
 30. The method of claim 27 wherein the spacingbetween the tibial and femoral cuts established by the connected cutguides is equal to the total thickness of a joint implant to be insertedinto the joint.
 31. A method for guiding a cutter to cut bone adjacent aknee joint to prepare the bone to receive an implant, the knee jointincluding articulating ends of a tibia and a femur and having a medialaspect, a lateral aspect, an anterior aspect, and a posterior aspect,the tibia having a tibial axis extending from a proximal end near theknee joint to a distal end near an ankle joint, the method comprising:providing a resection guide comprising a tibial cut guide having meansfor guiding a cutter to cut the tibia, a femoral cut guide mounted onthe tibial cut guide in relative mediolateral translating relationship,the femoral cut guide comprising means for guiding a cutter to cut thefemur; positioning the resection guide adjacent the tibia; translatingthe tibial cut guide mediolaterally to a desired mediolateral positionrelative to the tibia; and translating the femoral cut guidemediolaterally relative to the tibial cut guide to a desiredmediolateral position relative to the femur.
 32. The method of claim 28further comprising: positioning the femoral and tibial cut guidessimultaneously proximal-distally by moving the cut guides together as aunit and referencing the proximal tibial surface to set the resectionlevel for both guides.
 33. The method of claim 28 further comprising:positioning the femoral and tibial cut guides simultaneouslyproximal-distally by moving the cut guides together as a unit andreferencing the femur to set the resection level for both guides. 34.The method of claim 31 wherein the resection guide further comprises abase member alignable parallel to the tibial axis, the tibial cut guidebeing mounted on the base member in relative mediolateral translatingrelationship, the step of positioning the resection guide includespositioning the resection guide adjacent the tibia with the base memberaligned parallel to the tibial axis, and the step of translating thetibial cut guide includes translating the tibial cut guidemediolaterally relative to the base member.
 35. The method of claim 34wherein the resection guide further comprises an ankle clamp, the basemember being mounted on the ankle clamp in relative mediolateraltranslating relationship, the step of positioning the resection guidefurther includes positioning the ankle clamp around the ankle andtranslating the base member mediolaterally relative to the ankle clamp.